Pump noise control



R. F. TODD 2,813,543

PUMP NOISE CONTROL Filed July 28, 1955 Nov. 19, 1957 INVENTOR.

RICHARD F Tum] A TTURNE Y United States Patent PUMP NOISE CONTROL Application July 28, 1955, Serial No. 524,998 i 1 Claim. (Cl. 137-5133) This invention relates to washing machines having centrifugal drain pumps and more particularly to the elimination of pump gurgle in such washing machines.

In washing machines having a centrifugal drain pump, it is usual to continuously operate the centrifugal pump during an entire wash cycle and to cause the pump discharge to deliver the waste water into set tubs, which are located at an elevation above the pump. Under such circumstances the centrifugal pump is active only at times when water is to be drained from the wash tub. Following each draining operation, the pump is unable to clear the discharge hose of water beyond the pump. The column of water remaining in the discharge hose tends to surge back and forth between the pump impeller and the elevated discharge end of the discharge hose. While doing so, the pump intake is free of water and is generally directly open to the empty wash tub. The impeller also draws in air and drives the air up through the column of water. The periodic gurgling sound generated by the impeller and the air driven through the column each time the water surges back into the impeller, is emitted through the open pump intake, and thence to the tub. The pump intake is generally flared toward the tub, and the combination of the flared intake, and the empty wash tub results in a sound amplification system, which produces an unpleasant gurgling noise of considerable amplitude.

It is an object of the present invention to eliminate or prevent to a considerable extent the emission of pump gurgling noises from being emitted through the open pump intake and it is a further object of the invention to accomplish such result by a relatively simple inexpensive means which will in no way interfere with the normal operation of such pump, when wash water is to be quickly drained and discharged from the tub.

The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood that the drawings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings wherein like reference characters indicate like parts:

Figure 1 is a side elevational view of a typical washing machine and set tub used for drain purposes, part of the washer cabinet being broken away to expose the drain system parts;

Figure 2 is a sectional view taken through the flared end of the pump inlet taken substantially on the line 2-2;

Figure 3 is a plan view of a check valve and bleed disc applied to the inlet shown in Figure 2; and

Figure 4 is a sectional view taken substantially on the broken line 4-4 of Figure 3.

In Figure 1, there is shown a cabinet containing therewithin a wash tub 12, a centrifugal pump 14, having a belt drive 16 for continuous operation during a ICC washing cycle, and a pump inlet conduit 18. Alsothere is shown a discharge conduit 20, the end of which is hooked as at 22 to conveniently hang over-the edge of a set tub 24 from which drainage is had by gravity to the usual sewer system, through an outlet indicated at 26.

The inlet connection is generally formed. of flexible plastic or rubber like material which maybe molded to shape. Such inlet connection or conduit 18 is coupled to the tub drain aperture 28 in the bottom of the wash tub 12 by a cooperating exterior annular groove 30 in the conduit end into which is received the circular marginal edge of the tub drain aperture 28. A ferrule 32 is applied to the mouth of the drain conduit to hold the same expanded into place. Such ferrule has a curved flange 34 along its upper edge, and an annular ridge 36 located below the plane of the tub bottom. Such annular ridge provides on the inside an annular groove 37.

To block the emanation of sound from the pump, upwardly through the conduit and through the flair 38 thereof whence such amplified sounds enter the tub 12 and becomes further amplified by the drum diaphragm nature of the tub, there is placed in the annular groove 37, a flexible rubber disc having an annular marginal head 40 adapted to fit in the groove 37. The central web portion 41 of the disc is radially slitted as at 44 and to one side there is provided a port 46, such aperture being formed in a thickened portion of the disc as at 48.

It will be seen that under the conditions when there is no water in the tub or inlet conduit, that the resilient nature of the fingers 50 formed by the slits 44 is such as to close the aperture, leaving only the small port 46 open at all times. The closed fingers are suflicient to block the travel of sound waves emanating from pump gurgle below the disc, and the small port 46 is insufiicient to permit any appreciable sound of the activity of the pump from escaping.

Further, the disc has the effect of damping the flow of air into or out of the inlet conduit. Thus, as the pump impeller tends to kick the water trapped in the outlet conduit toward the outlet end thereof, necessary air to displace the water so moved is allowed to enter the puinpby the restricted port 46. Similarly as the water thrust up the outlet conduit commences to flow back to reengage the pump impeller, air is allowed to flow out of the inlet in a restricted manner by the port 46.

Thus, the period and violence or amplitude of the surge of the trapped water in the outlet conduit is reduced to a minimum, thus reducing the gurgling noise generated to a low level. At the same time such noise as does result from the pump impeller blades impinging on the column of water in the outlet pipe, is eflectively prevented from being amplified, or from escaping freely through the inlet conduit, and the damping effect tends to result in elimination of the periodic surge, so that any operational noise becomes steady and of low amplitude.

In fact, it is believed that the damping efiect of the disc while permitting entrance of some air tends to cause the pump to hold the lower end of the column of water in the outlet conduit in substance beyond the reach of the impeller blades so that the gurgling noise is substantially eliminated at its source.

While a single embodiment of the invention has been illustrated and described, it is to be understood that the invention is not limited thereto. As various changes in the construction and arrangement may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claim for a definition of the limits of the invention.

What is claimed is:

An outlet connection for the tub of a washing machine adapted to form a connection between a tub outlet aperture and a centrifugal drain pump comprising, a resilient tubular member, having at one end an external flange with an annular external groove adapted to embrace the marginal edge ofia'tub bottom aperture, a sleeve inserted into thefianged end: of. said tubular member to retain the endexpandedwhen. the groove ofsaid flange is in embracing position-with respect-to a tub aperture marginal edge, saidlsleeve-having an annular outwardly extending groove formed therein, and a circular valve disc of resilient materialseated in said groove, said disc having an annular bead seated in said groove and a web having radial slits'to providedistendable fingers adapted to open to allow the flow ofwater therethrough, and said disc having a constantly open bypass port therein for the flow of air therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 2,057,624 Burkhart Oct. 13, 1936 2,320,906 Bent June 1, 1943 2,322,631 Groeniger -2 June 22, 1943 2,341,894 Barifii Feb. 15, 1944 2,347,988 Burke May 2, 1944 2,629,393 Lang'don Feb. 24, 1953 2,663,309 Filliung Dec. 22, 1953 

